Wednesday, September 15, 2010

Peri-glacial evidence

Last weekend we were hiking across the north facing slopes in a basin at about 13,000 feet when I saw these great examples of protalus ramparts. At one time there was a permanent snowfield above the piles of rock. Erosion happens (is that a band or a bumper sticker?) easily in the rotten San Juan Mountains of SW Colorado. The mountains fall apart easily with all of the freeze-thaw cycles that occur. The material falls with the help of gravity and rolls right down the snow bank coming to rest at the base of the snow. Now that the snow is gone we see hills of rough, angular debris that does not touch the "parent" slope.

Evidence of a colder time.

A straight on view.You can see that there is no cirque above the debris hill suggesting that this is not a moraine.

Another protalus rampart in the same vicinity. In this case, the oblique view allows you to see behind the debris hill.Another example in the same basin and approximately the same aspect. No shortage of the raw material for talus.Just had to add the picture of the lake.